A genome‐scale analysis of mRNA s targeting to plant mitochondria: upstream AUG s in 5' untranslated regions reduce mitochondrial association

Summary Intracellular sorting of mRNA s is an essential process for regulating gene expression and protein localization. Most mitochondrial proteins are nuclear‐encoded and imported into the mitochondria through post‐translational or co‐translational processes. In the latter case, mRNA s are found to be enriched in the vicinity of mitochondria. A genome‐scale analysis of mRNA s associated with mitochondria has been performed to determine plant cytosolic mRNA s targeted to the mitochondrial surface. Many messengers encoding mitochondrial proteins were found associated with mitochondria. These mRNA s correspond to particular functions and complexes, such as respiration or mitoribosomes, which indicates a coordinated control of mRNA localization within metabolic pathways. In addition, upstream AUG s in 5' untranslated regions ( UTR s), which modulate the translation efficiency of downstream sequences, were found to negatively affect the association of mRNA s with mitochondria. A mutational approach coupled with in vivo mRNA visualization confirmed this observation. Moreover, this technique allowed the identification of 3'‐ UTR s as another essential element for mRNA localization at the mitochondrial surface. Therefore, this work offers new insights into the mechanism, function and regulation of the association of cytosolic mRNA s with plant mitochondria.